1. Field of the Invention
This invention relates to surgical instruments. More particularly, it relates to a cannula having a tip that does not break or chip when used in a surgical procedure.
2. Description of the Prior Art
An anchor is an implant used in orthopedic surgery. It is screwed into a humeral head by a surgeon performing a rotator cuff repair or into the glenoid if performing a labral repair.
Cannulas are commonly used in arthroscopic surgery. The distal end of a conventional cannula terminates in a tip having a sharp inner edge. When a suture is used, it can rub against such sharp inner edge. Such rubbing frays the suture and reduces its strength. The rubbing can also cause the suture to break. If the suture is secured to an anchor, the patient is charged for an additional suture and a new anchor. Depending upon the manufacturer, an anchor to repair a rotator cuff or labrum ranges from $150.00 to $400.00. When the suture of an anchor breaks, another anchor needs to be opened to complete the repair. This causes an additional cost to the hospital and the patient.
Moreover, the replacement anchor will not be as ideally positioned as the first, no-longer-usable anchor because the surgeon will have positioned the first anchor in an optimal location. The second anchor will thus be positioned in a second-best location.
Thus there is a need for a cannula that does not have a sharp inner edge at its distal end so that sutures are not frayed or broken by said cannula and so that a need for a second anchor will not arise.
Conventional cannulas are also subject to breakage at their distal tip. Breakage may occur if a surgeon hits a bone with sufficient force to cause such breakage. Introducing an orthopedic instrument into the lumen of the cannula during arthroscopic repair of a rotator cuff or labrum may also break the tip of a conventional cannula. If the cannula is chipped during such a procedure, the result is a loose body of plastic floating around in the shoulder joint of the patient. The plastic must be removed and such removal can take a long time. It is not uncommon for a surgeon to spend an hour trying to locate and remove a small piece of transparent plastic. The patient must remain under anesthesia during such time. With a typical operating room costing about $60.00 per minute, an hour of searching causes an extra $3600.00 charge.
There is a need, therefore, for a cannula having a tip that will not break during surgery.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the identified needs could be met.